Lubricating compositions containing a synergistic mixture of additives



United States Patent 838,696 1 Claim. (Cl. 252-466) This invention relates to oil compositions which have an improved capacity for maintaining the cleanliness of internal combustion engines in which they are used, and which contain (A) a phosphosulphurized hydrocarbon further reacted with an alkylene oxide, and (B) a nonmetal containing oil-soluble copolymer derived from two or more unsaturated copolymerizable monomer-s, at least one of which contains an oxygenor nitrogen-containing polar group.

The operation of internal combustion engines using fuels and lubricating oils containing carbonaceous compounds results in a progressive deterioration of the working parts. Thus, the metal surfaces of the engine may become covered with varnish, and carbonaceous deposits may develop, resulting in a tendency to increase wear of the engine and to reduce operating efficiency. It has previously been known to add non-metal containing compounds to lubricating oils to reduce wear. It has now been discovered that the cleanliness of internal combustion engines may be further improved to a synergistic degree by a combination of two additives as hereinafter described.

The type (A) additive incorporated in the oil composition of this invention consists :of a phosphosulphurized hydrocarbon further reacted with a C -C alkylene oxide. Amongst the hydrocarbons from which the aforesaid type (A) additives may be derived are paraffins, olefins or polymer-s thereof, diolefines, 'acetylenic hydrocarbons, alkyl-aromatic or cycloaliphatic hydrocarbons, and petroleum fractions such as mineral lubricating oils, bright stocks and waxes. The preferred hydrocarbons 'are brightstocks and poly-olefins, particularly isobutylene having a molecular weightof about 800 to 1600.

In preparing the type (A) compounds the hydrocarbon may be reacted with phosphorus sulphide, for example, P S or a mixture of elemental phosphorus and sulphur, at a temperature between about 190 and 600 F., preferably between 300 and 550 F. The time of reaction may vary between about 1 hour to hours, according to the degree 'of reaction desired. Thus from 1 to 10, preferably 2 to 5 mols of hydrocarbon may be reacted with one mol of phosphorus sulphide. The reaction is preferably carried out in a non-oxidizing atmosphere, for instance nitrogen.

After the desired degree of phosphosulphurization has taken place, the product is then further reacted with a C -C alkylene oxide, preferably ethylene oxide. alkoxylation may be carried out at elevated temperature, e.g. 230300 F., in the presence of a suitable catalyst, such as a boron 'trifluoride-ether complex or caustic soda, for an extended period of time, e.g., 1 to 5 hours, until the degree of alkoxylation required has been achieved.

, 1 to 10 mols of alkylene oxide may be reacted with one mol of phosphosulphurized hydrocarbon. The stability of the final product may be increased by steam-stripping the phosphosulphurized product prior to reaction with the alkylene oxide.

The type (B) additives incorporated in the oil composition of this invention are essentially the so-called ashless dipersants hitherto employed in lubricating oils,

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and consist primarily of copolymeric compounds derived from two or more monomers, at least one of which consists of a polymerizable unsaturated compound containing an oxygenor nitrogen-containing polar group.

The aforesaid oxygenor nitrogen-containing polar group may be an ester of a saturated mono-carboxylic acid with vinyl alcohol. Preferably however it is a derivative of an nap-unsaturated dicar-boxylic acid, particu uarly maleic acid, for instance m-aleic anhydride or a maleic acid ester, including a partial ester in which the remaining acid group may remain free or reacted with a further compound, for instance an alkylene oxide.

Other polar compounds include amines, amino-acids,

amides, N-vinyl butyrolactams, for example, N-vinyl pyrollidone, pyridines and substituted pyridines.

The copolymers may consist of two or more polar monomers hereinbefore enumerated by example, for instance, a copolymer derived from N-vinyl pyrollidone and a pyridine. Preferably however at least one of the monomers consists of an alkyl ester of an a-B-unsaturated carboxylic acid. Thus a mono-carboxylic acidsuch as acrylic, alkyl acrylic, itaconic, or a dicarboxylic acid such as maleic or fumaric acid may be esterified with an aloh-ol, e.g., a C C alcohol or alcohol mixture obtained for instance from natural sources, such as coconut oil, or derived by synthesis, as for example by the oxonation of olefines and the subsequent hydrogenation of the aldehyde thus produced.

The copolymeric additives which constitute the type B additives hereinbefore described are not confined to two-component copolymers, but may be derived from three or more monomers. They may be derived from an alkyl ester of an u-fi-unsatur-ated carboxylic acid and two or more polar monomers. Particularly useful copolymers are those derived from one or more C -C alkyl esters of maleic or fumaric acid, together with an ester of vinyl alcohol and a C -C mon ocarboxylic acid, and one or more further polar monomers, particularly maleic anhydride, partial esters of maleic acid as hereinbefore described, an unsaturated nitrile or N- vinyl pyrollidone.

Specific formulations of the latter type of type B copolymeric additives are derived from the following monomers.

Esters of fumaric or maleic acid and one or more C C alcohols, 160% by weight,

Esters of fumaric or maleic acid and one or more C C monohydric alcohols, 160% by weight,

Partial ester of maleic acid and one or more C C mon ohydric alcohols, 0.1 to 20% by weight,

Ester of vinyl alcohol and one or more C -C monocarboxylic acid, 180% by weight The compositions of this invention are particularly suitable for use as fuels or lubricants in internal combustion engines. The A and B type additives are each present in proportions of from 0.05 to 10% by weight. The total of the two components is preferably about 01-15%, more preferably 0.5-5 by weight, based on the total lubricating or fuel compositions. However, the compositions according to this invention also include concentrates containing substantially greater proportions of the addtive components, which may then be diluted with further oil to obtain compositions suitable for use in internal combustion engines, including fourstroke or two-stroke spark ignition or compression ignition engines. However, lubricating compositions of this invention are not confined to those using an automotive lubricating oil, but may be based on cutting oils, including emulsion-type lubricating oils, hydraulic fluids, kerosine-b-ased lubricating or fuel oils and spindle oils. The base oils may be mineral lubricating or fuel oils, or may be synthetic oils, including oxidized mineral oils, monoor di-esters for example dioctyl adipate or sebacate, complex esters, including complex esters derived from a mixture of monoor di-oarboxylic acids, monoor di-hydroxy alcohols, and a polyalkylene glycol or glycol ether, or mixtures of such synthetic oils, or the base oils may be of animal or vegetable origin, for instance castor oil or fish oils.

The oil composition of this invention may contain other additive constituents which are commonly added to fuel or lubricating oils. Thus oil-soluble anti-oxidant compounds may be incorporated, for instance aor 3- naphthylamine, including alkyl substituted derivatives thereof, alkyl phenols, for instance 2,4-dimethyl-6-tert. octyl phenol, substituted diphenylamines, including dioctyl dip'henylamine, and bisphenols. Extreme-pressure additives, such as alkylor aryl-substituted phosphates and phosphites, 'sulphurized hydrocarbons, sulphurized sperm oil or metal dialkyl dithiophosphates may be included in the compositions, as may also be polyisoolefines or degraded rubbery copolymers and other compounds which act as viscosity index improvers.

Having now described the invention, reference may be made to the following examples thereof, and experiments which illustrate the advantages to be obtained thereby.

Tests on engine cleanliness using the Petter A.V.I. test described in the Journal Inst. of PetroleumAept. 1953, were carriedout on a base oil, the base :oil containing a type A additive (Blend A), the base oil containing a type B additive (Blend B) and compositions according to the invention containing a mixture of type A and B additives (Blend C). The total merit figure for engine cleanliness of all parts inspected was taken without any washing of the parts inspected.

The -following additive components were used in the above tests. Blend: Component A Alkoxylated phosphosulphurized polybutene (designated Component A) obtained by reacting polyisobutylene of molecular weight 1,200 with 15% by weight of P S for 8 hours at 430 F., diluting the resultant product in 100 parts of mineral oil, steam stripping for 4 hours at 250 F., and further reacting the resulting product with 8 parts of ethylene oxide at 340 F. for 3 hours with the aid of a BF ether complex. B1 Copolymer (designated copolymer B1) obtained by copolymerizing a mixture of -0 alcohol fumarates, butyl half ester of maleic acid and vinyl acetate, using azodi-isobutyronitrile catalyst, the polymerization being carried out in a mineral oil diluent at 175 F. B2 Copolymer (designated copolymer B2) obtained by reacting a mixture of C -C alcohol fumarate, vinyl acetate and maleic anhydride, the polymerization being carried out in a mineral oil diluent using a benzoyl peroxide catalyst.

All blends tested were dissolved in a mineral base oil of viscosity 13 cs. at 210 F., and a viscosity index of 101.

The results of the engine tests are given in the accompanying table.

TABLE Total Petter AVI Lubricating oil blend: Merit Rating Base oil 60 Blend A containing 4%. of additive A 88 Blend B1 containing 4% of copolymer B1 74 Blend C containing 2% of additive A 2% of copolymer B1 96 Blend B2 containing 9% of copolymer B2 65 Blend C2 containing 4% of additive A of copolymer B2 98 It will be seen from the table that a synergistic effect on the cleanliness of the Petter engine was obtained by the use of a combination of additives of Type A and Type B hereinbefore described, over the use of such additives separately.

What is claimed is:

A lubricating oil composition suitable for use in an internal combustion engine comprising a major proportion of a mineral lubricating oil and a synergistic mixture with regard to engine cleanliness of (a) in the range of 0.05 to 4.0 wt. percent of a phosphosulphurized hydrocarbon alkylene oxide lubricating oil additive prepared by reacting mole of phosphosulp-hurized hydrocarbon with from 1 to 10 moles of a C -C alkylene oxide at 230 to 340 F. for about 1 to 5 hours and (b) in the range of 0.05 to 10 wt. percent of oil-soluble ashless dispersant lubricating oil additive prepared by cop-olymerizing:

- from 1 to 60 Wt. percent of a mixture of C '-C alcohol fumarates, from 0.1 to 20 wt. percent of a butyl half 40 ester of maleic acid and from 1 to 80 wt. percent of vinyl acetate in a mineral oil diluent.

References Cited by the Examiner UNITED STATES PATENTS 2,694,685 11/1954 Bartlett et al. 25256 7 FOREIGN PATENTS 758,203 10/1956 Great Britain. 792,553 3/1958 Great Britain.

797,266 6/1958 Great Britain.

807,737 1/ 1959 Great Britain. 808,665 2/1959 Great Britain. 838,928 6/1960 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner.

I. R. SEILER, L. G. XIARHOS, Assistant Examiners. 

